1. Field of the Invention
The present invention relates to a head slider capable of suppressing the variation and irregularity of flying height, or the variation of contact pressure, and a read/write apparatus provided with such a head slider for supporting a read/write head at a low flying height or supporting a read/write head in small-force, stable contact with a recording medium to enable recording in a high recording density.
2. Description of the Prior Art
In recent years, read/write apparatuses have been actively developed to enhance the recording density thereof. In particular, the recording density of a magnetic disk drive is enhanced by both of the increase of bit density (the recording density in circumferential directions of a disk) and the increase of track density (the recording density in radial directions of the disk). In order to increase the bit density, it is required to decrease the flying height of a head slider (which will be hereinafter referred to as a "slider"), on which a read/write head (which will be hereinafter referred to as a "head") is mounted. However, in conventional sliders, the dynamic variation in flying height during a seek operation (e.g., to scan a head to move the head to a position at which designated information is stored) prevents the flying height of the head from decreasing. The factors thereof will be described in detail below.
FIG. 34 schematically illustrates a magnetic disk drive using a conventional slider. In most of conventional sliders 101 represented by a so-called taper flat slider, the difference in flying height is inhibited from occurring due to the difference between the inner and outer peripheral velocities of a disk 102 serving as a recording medium, using the yaw angle dependence. The yaw angle means an angle (.theta. in the drawing) defined between the rotating direction of the disk and the longitudinal direction of the slider 101.
As shown in FIG. 34, in a magnetic disk drive using a so-called rotary actuator 103, the slider 101 and the disk 102 are arranged so that the yaw angle on the side of the inner peripheral portion X of the disk is smaller than the yaw angle on the outer peripheral portion Y of the disk.
FIG. 35 is a perspective view schematically illustrating a conventional taper flat slider. As shown in FIG. 35, the slider 101 has elongated dynamic pressure generating parts 101a, which extend in a disk rotating direction A, and serves to fly a head using the dynamic pressure generated between the power generating portions 101a and the rotating disk (not shown). The pressure generating efficiency of the dynamic-pressure generating parts 101a extending in the disk rotating direction A decreases when the yaw angle is formed to change the disk rotating angle from A to B in FIG. 35. Because, when the yaw angle is small, air flowing onto the slider from the slider front end flows along the whole length of the slider by a relatively long distance to generate a dynamic pressure, whereas when the yaw angle increases, it is difficult to ensure the flowing distance required to effectively increase the dynamic pressure due to a so-called transverse leakage of air flow that a part of the air flows out of the side edge before completely flowing the whole length of the slider or air flows into the side edge to flow out of the rear end. Therefore, in the conventional taper flat slider 101, when the yaw angle increases as the slider approaches the outer peripheral portion Y of the disk, the dynamic-pressure generating efficiency on the slider 101 decreases due to the transverse leakage of air flow. Therefore, even if the peripheral velocity increases as the slider approaches the outer peripheral portion Y of the disk, the flying force exerting on the slider 101 does not vary, so that it is possible to decrease the difference in flying height between the inner and outer peripheral portions of the disk 102.
As shown in FIG. 36, when the seek of the slider 101 is carried out, a seek velocity component Vs (about 1 m/s at a maximum) substantially perpendicular to a disk rotation velocity component Vr (5 to 10 m/s) exists in addition to the disk rotation velocity component Vr. Therefore, the composite vector V of these two velocity components has an angle of about 5.degree. to 10.degree. to the longitudinal directions of the slider 101. That is, an equivalent yaw-angle variation (.theta. in FIG. 36) occurs during a seek operation.
Therefore, in accordance with the same principle as the aforementioned yaw angle dependence, the dynamic-pressure generating efficiency decreases due to the transverse leakage of air flow during the seek operation, so that the flying height decreases transiently. It is experimentally verified that the decreasing flying height usually exceeds 10 nm. Therefore, in order to prevent the disk from colliding with the slider during the seek operation, a spacing (a flying gap) allowing for a margin of decreasing flying height must be set. This causes to prevent the flying height of the slider from decreasing.
At the present time, in order to further improve the recording density, the contact recording technique for bringing a head into contact with a disk to carry out the reading and/or writing at a flying height of substantially zero has been studied. The most important problem to be solved in this contact recording technique is to reduce the abrasion of the head. In order to eliminate this problem, it is required to maintain weak and stable contact force exerting between the head and the disk. However, as described above, the conventional slider can not maintain weak and stable contact force exerting between the head and the disk since the contact force varies by the equivalent yaw-angle variation during the seek operation. In addition, when the abrasion of the head is in progress, if the flying attitude varies above the inner and outer peripheral portions of the disk, the contact portion may fly to form a spacing.
Moreover, in a case where a so-called MR head using a magneto-resistance effect element, which has newly made fit for practical use and which will be the mainstream in future, is used, it is required to separately provide a reading head and a writing head, and the two heads are usually arranged in the track direction. With this construction, if the yaw angles of the inner and outer peripheral portions vary greatly, a deviation in the lateral direction of a track (a track deviation) occurs between the two heads. In order to eliminate this problem, a method for using a linear actuator and a method for optimizing the length of an actuator arm to decrease the variation in yaw angle (see Japanese Patent Laid-Open No. 5-298615) have been studied. Therefore, also in the case of a slider using the MR head, there is a great possibility that it is required to suppress the difference in flying height between the inner and outer peripheral portions of the disk without utilizing the yaw angle dependence.
As described above, since the conventional slider has a shape suitable for the suppression of the difference between the flying heights in the inner and outer peripheral portions of the disk utilizing the yaw angle dependence, the decrease of the flying height or the variation in contact force occurs due to the equivalent yaw-angle variation during a seek operation. Therefore, it is difficult to decrease the flying height of the head or to achieve the weak and stable contact between the head and the disk.
In addition, when the abrasion of the head is in progress in the contact recording, if the flying attitude above the inner and outer peripheral portions of the disk varies, the contact portion may fly to form a spacing.
Moreover, in a slider using a MR head, it is requested to provide the technique for suppressing the difference in flying height above the inner and outer peripheral portions of a disk without utilizing the yaw angle dependence.